docs: Windows port README should include `make submodule` as a build step

[mattytrentini]

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Documentation URL

https://github.com/micropython/micropython/blob/master/ports/windows/README.md

Description

The build steps for the Windows port are missing make submodule. Build errors occur because micropython-lib (specifically the ssl module) isn't found if that command isn't executed.

[PolarGoose]

Indeed, if I execute msbuild ports/windows/micropython.vcxproj /p:PyVariant=standard I get the following error:

FreezeModules:
  python C:\my\gitrepos\micropython-1.23.0\tools\makemanifest.py -v MPY_DIR=C:\my\gitrepos\micropython-1.23.0\ -v MPY_LIB_DIR=C:\my\gitrepos\micropython-1.23.0\/lib/micropython-lib -v PORT_DIR=C:\my\gitrepos\micropython-1.23.0\ports\wi
  ndows\ -o C:\my\gitrepos\micropython-1.23.0\ports\windows\build-standard\frozen_content.c -b C:\my\gitrepos\micropython-1.23.0\ports\windows\build-standard\ C:\my\gitrepos\micropython-1.23.0\ports\windows\\variants\manifest.py
  freeze error executing "C:\my\gitrepos\micropython-1.23.0\ports\windows\\variants\manifest.py": Error in manifest file: C:\my\gitrepos\micropython-1.23.0\ports\windows\variants\manifest.py: Package 'ssl' not found in any known librar
  y.
C:\my\gitrepos\micropython-1.23.0\ports\windows\msvc\genhdr.targets(175,5): error MSB3073: The command "python C:\my\gitrepos\micropython-1.23.0\tools\makemanifest.py -v MPY_DIR=C:\my\gitrepos\micropython-1.23.0\ -v MPY_LIB_DIR=C:\my\g
itrepos\micropython-1.23.0\/lib/micropython-lib -v PORT_DIR=C:\my\gitrepos\micropython-1.23.0\ports\windows\ -o C:\my\gitrepos\micropython-1.23.0\ports\windows\build-standard\frozen_content.c -b C:\my\gitrepos\micropython-1.23.0\ports\
windows\build-standard\ C:\my\gitrepos\micropython-1.23.0\ports\windows\\variants\manifest.py" exited with code 1. [C:\my\gitrepos\micropython-1.23.0\ports\windows\micropython.vcxproj]
Done Building Project "C:\my\gitrepos\micropython-1.23.0\ports\windows\micropython.vcxproj" (default targets) -- FAILED.

MSVC toolchain doesn't contain make. How can I do make submodule on Windows?

[stinos]

You need to run git submodule update --init lib/micropython-lib or similar

I have a commit in this PR which adds support for doing this automatically when building in VS and adds an msbuild target: https://github.com/micropython/micropython/pull/12810/commits

Maybe that commit should be split off in a separate PR?

[PolarGoose]

@stinos,

Thank you for the hint. Yes, with this command, the build works.
I have created a repository that creates a Windows binary: MicroPython-for-Windows